string theory

string theory, description of elementary particles based on one-dimensional curves, or "strings," instead of point particles. Superstring theory, which is string theory that contains a kind of symmetry known as supersymmetry, shows promise as a way of unifying the four known fundamental forces of nature. The strings are embedded in a space-time having as many as 10 dimensions—the three ordinary dimensions plus time and seven compactified dimensions. The energy-scale at which the stringlike properties would become evident is so high that it is currently unclear how any of the forms of the theory could be tested.